In general, silicone rubber compositions possess a mold releasing property. Therefore, when they are utilized to bond metals or to adhere to other substrates such as glass, ceramics, plastics, fibers, and rubbers under ordinary vulcanization conditions, it is first necessary to treat such surfaces with a primer. However, the additional treatment step by a primer makes the forming process more complicated. In addition, the primers normally utilized are organic solvent solutions. Such solutions necessitate a facility for the exhaust of organic solvent vapors generated from the forming processes. Further, they can also cause health hazard problems from the absorption of organic solvent gas by operators through breathing and skin contact which may induce internal diseases. Further, some forming conditions, such as in the injection forming process where a strong shear force is applied, also have problems of primer layer effluence and peeling. As a result, the demand is high for self-adhesive silicone rubber compositions which do not require a primer treatment.
Conventionally, self-adhesive silicone rubber compositions have been known to comprise the following chemicals as a component to provide adhesivity: peroxy silanes such as a vinyl tris(t-butyl peroxy) silane, triphenyl (t-butyl peroxy) silane, trimethyl (t-butyl peroxy) silane, and methyl vinyl di(t-butyl peroxy) silane; and silane coupling agents such as a vinyl trimethoxy silane, vinyl triethoxy silane, .gamma.glycidoxy propyl trimethoxy silane, and .gamma.-methacryloxy propyl trimethoxy silane.
However, these self-adhesive-type silicone rubber compositions have not possessed a satisfactory level of the self-adhesivity. Therefore, the purpose of this invention is to provide self-adhesive silicon compositions which possess a strong adhesivity towards various types of substrates without using special types of primers.